Software maintenance is important and difficult to measure. The cost of maintenance is the most ever during the phases of software development. One of the most critical processes in software development is the reduction of software maintainability cost based on the quality of source code during design step, however, a lack of quality models and measures can help asses the quality attributes of software maintainability process. Software maintainability suffers from a number of challenges such as lack source code understanding, quality of software code, and adherence to programming standards in maintenance. This work describes model based-factors to assess the software maintenance, explains the steps followed to obtain and validate them. Such a method can be used to eliminate the software maintenance cost. The research results will enhance the quality of the source code. It will increase software understandability, eliminate maintenance time, cost, and give confidence for software reusability.